Integration and unit tests no longer work on ASP.NET Core 2.1 failing to find assemblies at runtime
When creating test projects or upgrading an application and tests to ASP.NET Core 2.1 / .NET Core 2.1, running tests fails with assembly load exceptions like System.IO.FileNotFoundException : Could not load file or assembly 'Microsoft.AspNetCore, Version=2.1.0.0, Culture=neutral, PublicKeyToken=adb9793829ddae60'. The system cannot find the file specified. When adding references to some other libraries there are also build warnings like warning MSB3277: Found conflicts between different versions of "Microsoft.Extensions.Options" that could not be resolved. warning MSB3277: Found conflicts